Studies of the physical properties of 'intermediate' active
galactic nuclei are intriguing because of their potential to
test, and impact on, the the standard unification models of
active galactic nuclei (AGN). In particular, the unique
'glancing' viewing angle implied in these objects highlights
that they are the best, and possibly the only, sources that
allow us to study both the high column density, relatively
low ionization, absorbing material that may form the 'skin'
of the molecular torus or the material immediately interior
to the torus. The Seyfert 1.5 galaxy Markarian 6 (Mrk 6) was
first identified as an intermediate Seyfert through optical
spectroscopy by Osterbrock & Koski (1976) and is often
referred too as a ''4151 analogue''. The comparison of the
two recent XMM-Newton observations of Mrk 6 reveals that
whilst the original observation revealed complex heavy
column density absorption (~1023 cm-1),
similar to that of NGC 4151, the most recent observation
shows almost an order of magnitude less absorption. The
similar ionizing luminosities in the two observations
largely rules our significant absorption variability through
ionization and is strong evidence in favor of a patchy
structure for the absorbing material. A further degree of
complexity is possible if the patchy material of the
absorber is also partially ionized. Future observations of
heavy, complex absorption in bright, nearby sources,
particularly with Astro-EII, have the potential to
distinguish between a patch neutral and patchy partially
ionized absorption in similar sources.